The present invention relates generally to an electrical connector and, more particularly, to a low insertion force circular electrical connector.
The present invention comprises an improvement upon the low insertion force circular connector disclosed in U.S. Pat. No. 3,818,420 to John E. Barr, assigned to the assignee of the present application. The Barr patent discloses a circular connector having a pair of connectors each with a plurality of contacts therein. One of the connector members includes a stationary insulator and an activating disc, formed with a plurality of axially aligned bores therein receiving contacts. A rotatable shell surrounds the activating disc. The shell is formed with a cam tooth on the inner surface thereof. When the shell is rotated, the cam tooth cooperates with an arcuate cam surface on the activating disc to shift the disc with respect to the axes of the bores to interengage the electrical contacts in the respective connector members. The cam tooth loads the contacts in the last few degrees of rotation of the shell because the cam surface on the activating disc has a relatively hard rise angle. These characteristics cause excessive resistance and wear of the mating cam surfaces on the activating disc and shell, causing loss of mechanical integrity of the mated contacts after just a few actuations of the contacts in the connector. The loss of mechanical integrity of the contacts results in loss of electrical continuity in the connector. Also, this construction requires that the shell be formed of a relatively resilient material, thereby limiting the types of materials that can be utilized for manufacture of the shell. Further, this arrangement requires a high torque for mating of the two connector members.
The Barr patent also discloses an interlock arrangement for the two connector members of the connector. The shell on the plug connector member is formed with a pair of oppositely disposed teeth on the inner surface therein which engage in L-shaped grooves formed on the receptacle connector member. In a commercial embodiment of the Barr connector, raised areas are formed on the circumferentially extending portions of the L-shaped grooves, causing the shell to elongate when the shell is rotated to interconnect the contacts of the two connector members. When the shell reaches its fully mated position, it contracts or snaps back for retention and a tactile and audio indication of the fully mated condition of the connector. These characteristics may cause excessive torque and wear and again limits the type of material that can be utilized for the shell.
The purpose of the present invention is to overcome the attendant disadvantage of the aforementioned prior art zero force circular connector, by providing an arrangement which requires lower torque for mating the connector members together without loss of retention or tactile indication of the mating of the members. Another object of the invention is to improve the mechanical integrity of the connector in the areas of cam action, wear and resistance, so as to increase the useful life of the connector.